Method for manufacturing tobacco raw material, and tobacco raw material

ABSTRACT

Provided is a tobacco raw material having a low content of specified polycyclic aromatic hydrocarbons and low-molecular carboxylic acids and containing a large amount of specified flavor components, and a method for manufacturing the tobacco raw material. The objective is achieved with a manufacturing method including: a step for drying pre-deribbing leaf tobacco after harvesting until the moisture content thereof reaches 10-25 wt %; a step for smoke-processing the pre-deribbing dried tobacco using thermally decomposed smoke at 400-500° C.; and a step for, after the smoke-processing step, storing the pre-deribbing smoke-processed leaf tobacco under partially sealed conditions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2017/044045, filed on Dec. 7, 2017, which is claiming priority ofJapanese Patent Application No. 2017-014207, filed on Jan. 30, 2017, allof which are hereby expressly incorporated by reference into the presentapplication.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a method for manufacturing a tobaccomaterial and to a tobacco material.

Background Art

Efforts have already been made to improve the flavor of leaf tobacco asa raw material. For example, Tobacco Academic Studies Center, “TheEncyclopedia of Tobacco”, Japan, San-ai Shoin (Yugen Kaisha (Y.K.)),Mar. 31, 2009, First Edition, page 327 describes passing smoke from ricehusks or wood through shredded tobacco to impart a distinctive smokyaroma and describes the generation of smoke in this case by gentlyheating rice husks to gradually effect charring and burning.

Dark fire-cured (DFC) is known as a tobacco material that has undergonea smoke treatment. The general manufacturing method here is known toinclude a step of subjecting a raw tobacco leaf that has not undergone adrying treatment to a smoke treatment with smoke generated by thecombustion of, e.g., wood, at a heating/combustion temperature ofapproximately 600° C. to 900° C.; a subsequent fermentation step; and anensuing storage step after going through an ageing step.

DFC is used as a starting material for, e.g., snuff, pipe tobacco, andchewing tobacco.

Japanese Translation of PCT Application No. 2013-542744 describes atobacco product that uses an extract of a fire-cured tobacco and statesthat the content of the benzo[a]pyrene contained in ordinary fire-curedtobacco is approximately 150 to approximately 800 ng/g.

WO 2014/203341, meanwhile, describes the production of ester compoundsas brought about by the addition of an alcohol such as ethyl alcoholafter the execution of a smoke treatment on a dried leaf tobacco,followed by storage of the alcohol-added leaf tobacco to bring about anesterification reaction between organic acids provided by the smoketreatment and the subsequently added alcohol.

SUMMARY OF THE INVENTION

In The Encyclopedia of Tobacco, only ordinary smoking means and so forthare described as the methods for imparting a distinctive smoky aroma toa tobacco material such as shredded tobacco.

In the invention described in WO 2014/203341, the smoke treatment iscarried out on the dried leaf tobacco in order to provide the dried leaftobacco with substrates for the subsequent esterification reaction byproviding the cured leaf tobacco with the organic acids present in thesmoke, and the object of this invention is simply to increase the estercompounds in the tobacco material.

In contrast to this, the present invention addresses the problem ofproviding a tobacco material that exhibits a suppression of the adhesionto the leaf tobacco of the benzo[a]pyrene that can be produced in thecase of execution of the ordinary smoke treatments as heretofore carriedout, that exhibits a reduced content of low molecular weight carboxylicacids, and that exhibits an increase in specific flavor components, andof providing a method for manufacturing this tobacco material.

As a result of intensive investigations by the present inventor, it wasdiscovered that a tobacco material having a low content ofbenzo[a]pyrene, a low content of low molecular weight carboxylic acids,and a large content of specific flavor components, can be provided by amanufacturing method containing a step of drying a post-harvest,unstripped leaf tobacco to a moisture content of 10 to 25 wt %; a stepof subjecting the dried unstripped leaf tobacco to a smoke treatmentwith a smoke provided by the pyrolysis of a smoke-producing material ina material temperature range of 400° C. to 500° C.; and a step,subsequent to the smoke treatment step, of storing the smoke-treatedunstripped leaf tobacco under a semi-sealed condition. The presentinvention was achieved based on this discovery.

That is, embodiments of the present invention are as follows.

[1] A method for manufacturing a tobacco material, including the stepsof: drying a post-harvest unstripped leaf tobacco to a moisture contentof 10 to 25 wt %; subjecting the dried unstripped leaf tobacco to asmoke treatment with a smoke provided by pyrolysis of a smoke-producingmaterial in a material temperature range of 400° C. to 500° C.; and,subsequent to the smoke treatment step, storing the smoke-treatedunstripped leaf tobacco under a semi-sealed condition.

[2] The method for manufacturing a tobacco material according to [1],wherein the drying of the post-harvest unstripped leaf tobacco iscarried out to a moisture content thereof of 15 to 20 wt %.

[3] The method for manufacturing a tobacco material according to [1] or[2], wherein the storing step is carried out at room temperature for aduration of at least 3 months but less than 24 months.

[4] The method for manufacturing a tobacco material according to any of[1] to [3], wherein the tobacco material yielded by the manufacturingmethod has the following constitution:

(1) a benzo[a]pyrene content is not more than 100 ng/g based on the dryweight of the tobacco material;

(2) a acetic acid content is not more than 20 mg/g based on the dryweight of the tobacco material;

(3) a guaiacol content is 5 to 5,000 μg/g based on the dry weight of thetobacco material; and

(4) a 2,6-dimethoxyphenol content is 10 to 10,000 μg/g based on the dryweight of the tobacco material.

[5] A tobacco material constituted of a leaf tobacco that has not beensubjected to a lamina/stem separation process, wherein the tobaccomaterial has a constitution according to the following (1) to (4):

(1) a benzo[a]pyrene content is not more than 100 ng/g based on the dryweight of the tobacco material;

(2) an acetic acid content is not more than 20 mg/g based on the dryweight of the tobacco material;

(3) a guaiacol content is 5 to 5,000 μg/g based on the dry weight of thetobacco material; and

(4) a 2,6-dimethoxyphenol content is 10 to 10,000 μg/g based on the dryweight of the tobacco material.

[6] A tobacco product comprising the tobacco material according to [5].

[7] The tobacco product according to [6], which is a cigarette or aheating flavor inhaler.

Advantageous Effects of Invention

The present invention thus provides a tobacco material having a lowcontent of benzo[a]pyrene, a low content of low molecular weightcarboxylic acids, and a high content of specific flavor components, andprovides a method for manufacturing this tobacco material.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram that shows a general process formanufacturing a tobacco product.

FIG. 2 is a diagram that shows the relationship between the materialtemperature of a smoke-producing material and the content of thebenzo[a]pyrene contained in a leaf tobacco after a smoke treatment.

FIG. 3 is a diagram that shows the relationship between the materialtemperature of a smoke-producing material and the content of theguaiacol contained in a leaf tobacco after a smoke treatment.

FIG. 4 is a diagram that shows the relationship between the materialtemperature of a smoke-producing material and the content of the2,6-dimethoxyphenol contained in a leaf tobacco after a smoke treatment.

FIG. 5 is a schematic diagram of an apparatus used to measure theadhesion efficiency by specific flavor components to a leaf tobacco.

FIG. 6 is a diagram that shows the relationship between the moisturecontent of a pre-smoke-treatment leaf tobacco and the guaiacol adhesionefficiency.

FIG. 7 is a diagram that shows the relationship between the moisturecontent of a pre-smoke-treatment leaf tobacco and the2,6-dimethoxyphenol adhesion efficiency.

FIG. 8 is a diagram that shows the timewise change in the propionic acidcontent in leaf tobacco during storage under a semi-sealed condition andunder a sealed condition.

FIG. 9 is a diagram that shows the timewise change in the acetic acidcontent in leaf tobacco during storage under a semi-sealed condition andunder a sealed condition.

FIG. 10 is a diagram that shows the timewise change in the propionicacid content in leaf tobacco during storage (accelerated test) under asemi-sealed condition.

FIG. 11 is a diagram that shows the timewise change in the acetic acidcontent in leaf tobacco during storage (accelerated test) under asemi-sealed condition.

DESCRIPTION OF EMBODIMENTS

The present invention is described in detail in the following usingembodiments, examples, and so forth. However, the present invention isnot limited to or by the following embodiments, examples, and so forth,and can be executed using any variation or modification within a rangein which there is no departure from the essential features of thepresent invention.

FIG. 1 shows a common manufacturing process for a smoking article, e.g.,cigarettes and so forth.

In this manufacturing process, the harvested leaf tobacco is stored in awarehouse after undergoing a curing treatment.

This curing is a treatment that is carried out in a first stage on theharvested leaf tobacco, and it generally includes a step of drying,humidity conditioning, and so forth and may also include activation ofthe action of various enzymes present in leaf tobacco.

Curing is performed mainly for the following purposes: (1) increasingthe action of enzymes and causing the development of changes in the leafcolor; (2) drying the leaf lamina and fixing the leaf color; and (3)removing the moisture in the stem and drying out the leaf as a whole.

After this curing, storage in a warehouse is carried out for aprescribed period of time followed by transport of the leaf tobacco to amaterial processing site. Stripping of the leaf tobacco and separationare not carried out during curing, and these processes, e.g., strippingand so forth, are performed at the material processing site.

The manufacturing method according to embodiments of the presentinvention is carried out in place of this curing treatment, and thetobacco material provided by proceeding through the manufacturing methodaccording to embodiments of the present invention is generallytransported to the material processing site after warehouse storage.

In contrast to this, the manufacturing method described in WO2014/203341 is carried out on a tobacco material that has undergone thetreatments at the material processing site shown in FIG. 1. The reasonfor this is as follows: when the treatments commonly performed at thematerial processing site as shown in FIG. 1 are carried out on thetobacco material provided by the manufacturing method described in WO2014/203341, the ester compounds present in the tobacco material end upvaporizing due to the performance of treatments that are accompanied byheating, e.g., re-drying and so forth. This is also supported by thefact that the leaf tobacco treated by the manufacturing method describedin WO 2014/203341 is a “shredded tobacco”, for which the assumption ismade of having been processed at the material processing site of FIG. 1.

Based on the preceding, the manufacturing method described in WO2014/203341 and the manufacturing method according to embodiments of thepresent invention thus have completely different circumstances ofexecution.

In this Description, “leaf tobacco” indicates leaf tobacco prior to theexecution, or in the course of the execution, of the process accordingto the steps in the manufacturing method according to the presentinvention, while “tobacco material” designates the material that hasbeen processed.

<Step of Drying Post-Harvest Unstripped Leaf Tobacco>

The post-harvest unstripped leaf tobacco used for the tobacco materialaccording to embodiments of the present invention is leaf tobacco afterthe “harvesting” shown in FIG. 1, but prior to the occurrence of a colorchange such as yellowing, prior to the execution of the “curing”treatment, and prior to stripping.

There are no particular limitations on the leaf tobacco used in themanufacturing method according to embodiments of the present inventionor used for the tobacco material described in the following, andexamples here are genus Nicotiana and burley varieties, flue-curedvarieties, Oriental varieties, and domestic varieties of Nicotianatabacum and Brasilia varieties of Nicotiana rustica.

With the regard to the post-harvest leaf tobacco, the use isparticularly preferred of the leaf tobacco immediately after harvesting,and the drying treatment described below is preferably carried out onsuch leaf tobacco immediately after harvesting.

The post-harvest leaf tobacco (raw leaf) ordinarily has a high moisturecontent and has a moisture content of 80 to 90 wt % with reference tothe total amount of the leaf tobacco.

A drying treatment is carried out on this leaf tobacco until themoisture content reaches 10 to 25 wt %.

The lower limit for the moisture content of the leaf tobacco provided bythe drying treatment is more preferably 12 wt % and particularlypreferably is 15 wt %. When the range for the moisture content of theleaf tobacco is 15 to 25 wt %, a particularly excellent effect isobtained with regard to increasing the content (adhesion amount) of thespecific flavor components that are provided by the smoke. The upperlimit on the moisture content of the leaf tobacco can also be, forexample, 20 wt %.

The specific flavor components can be exemplified by guaiacol and2,6-dimethoxyphenol.

The moisture content in the leaf tobacco is determined using thefollowing method.

Based on a method for analyzing the moisture in foods (thermal dryingmethod), heating is carried out for 1 hour at 100° C. under normalpressure followed by spontaneous cooling in a desiccator for 40 minutes.The moisture is determined from the weight differencepre-versus-post-heating. The specific procedure is as follows.

(1) The empty weight of a sample container stored in the desiccator ismeasured.

(2) The necessary amount of the leaf tobacco is weighed out andintroduced into the sample container and the lid is applied.

(3) The lid of the sample container is removed, the sample container isplaced in a rotary drying vessel, and heating is carried out for 1 hourat 100° C.

(4) After 1 hour, the sample container is closed with the lid and isremoved and spontaneous cooling is carried out in a desiccator.

(5) After 40 minutes, the weight of the sample container is measured.The moisture is determined using the following formula.

${Mw} = {\frac{{W\; 1} - {W\; 2}}{{W\; 1} - {W\; 0}} \times 100}$

Mw: moisture (%)W1: weight of the sample container and pre-dried sample (g)W2: weight of the sample container and dried sample (g)W0: weight of the sample container (g)

There are no particular limitations on the drying treatment method, andthe following methods can be provided as examples.

In one method, the leaf tobacco is air-dried for approximately 1 monthat approximately 20° C. to 50° C., and preferably 25° C. to 35° C.,although this will vary depending on the region where the tobacco grows,in a drying room that is impermeable to direct sunlight, e.g., apipe-house, by suitable gapless row drying or stem drying such thatdrying unevenness cannot occur, while the air is undergoing naturalconvection.

In another method, drying is carried out for approximately 5 days at atemperature of approximately 30° C. to 70° C. and a relative humidity ofapproximately 20% to 100% in an apparatus such as a circulation bulkdryer that supports temperature and humidity control.

These two methods may also be used in combination.

In another method, drying is carried out for several hours with anapparatus at a drying temperature of approximately 100° C. in theapparatus compartment.

<Step of Performing Smoke Treatment>

In the step of subjecting the leaf tobacco to a smoke treatment, asmoke-producing material is heated so as to provide a materialtemperature for the smoke-producing material, e.g., wood, of 400° C. to500° C. in order to produce smoke as described in the following.

By heating to a material temperature for the smoke-producing material inthe range from 400° C. to 500° C., in contrast to the DFC manufacturingmethod described above, specific polycyclic aromatic hydrocarbons, forexample, benzo[a]pyrene, which are adhered in large amounts to the leaftobacco with DFC, can be reduced. On the other hand, by heating thesmoke-producing material so as to reach a material temperature of atleast 400° C., the pyrolysis of substances, for example, lignins,present in the smoke-producing material is promoted and specific flavorcomponents, and specifically guaiacol and 2,6-dimethoxyphenol, can beadhered to the leaf tobacco in satisfactory amounts.

The smoke-producing material can be exemplified by wood, and the typethereof is not particularly limited and can be, for example, white oak,cherry, walnut, apple, beech, oak, and hickory.

The duration of the smoke treatment can be adjusted as appropriate, forexample, in the range from approximately 10 minutes to 6 months.

All of these smoke treatments can be carried out using a known smokingdevice, smoking apparatus, and so forth. The smoke treatment can becarried out in a state where the leaf tobacco is stacked or the leaftobacco can be row dried or stem dried.

In the manufacturing method according to embodiments of the presentinvention, it is unnecessary to perform any treatment and/or to add anysubstance after the aforementioned smoke treatment step and before thestorage step described below in order to modify the properties of theleaf tobacco or the substances imparted by the smoke treatment. Such atreatment and such a substance addition are ordinarily not performed.

For example, the DFC manufacturing method described above includes afermentation step and an ageing step after performing the smoketreatment and before the storage step, whereas the method according tothe present invention do not include such a fermentation step and anaging step.

In addition, for example, the step of adding an alcohol in order toproduce ester compounds in a subsequent step, as described in WO2014/203341, is also not included in the manufacturing method accordingto the present invention.

Accordingly, the manufacturing method according to embodiments of thepresent invention contains the storage step described in the followingafter the step of subjecting the leaf tobacco to a smoke treatment andfollowing this smoke treatment step.

<Storage Step>

In order to volatilize low molecular weight carboxylic acids, e.g.,acetic acid, during storage, the step of storing the smoke-treatedunstripped leaf tobacco is carried out under a semi-sealed condition.

This semi-sealed condition can be, for example, a condition in which thesmoke-treated leaf tobacco is inserted into an air-permeable packingmaterial, such as a vinyl bag, and the opening of this packing materialis fold over, thereby impeding the inflow and outflow of air to acertain degree.

The storage of the leaf tobacco under semi-sealed conditions can beachieved by filling the packing material as described above with thesmoke-treated leaf tobacco and folding the opening over to produce aleaf tobacco-filled, semi-sealed packing material, and storing this leaftobacco-filled packing material in a storage container, e.g., acardboard carton.

In this storage, the storage of a large amount of the leaf tobacco at asingle time may be carried out by producing a plurality of the leaftobacco-filled packing materials and storing same stacked within astorage container.

By carrying out the storage step under semi-sealed conditions in thepresent invention, the content of low molecular weight carboxylic acidsin the resulting tobacco material can be reduced because low molecularweight carboxylic acids such as acetic acid, which can cause irritation,then undergo volatilization during storage.

The duration of storage should be a time interval that supports asatisfactory reduction in the low molecular weight carboxylic acids suchas acetic acid, but is not otherwise particularly limited, although atleast 3 months is preferred. The upper limit on the duration of storage,on the other hand, is preferably approximately 24 months considering thetime interval until the produced tobacco material is shipped to thematerial processing site.

The temperature during storage is preferably a temperature at which thelow molecular weight carboxylic acids undergo a satisfactoryvolatilization.

The specific temperature can be exemplified by room temperature. Thespecific temperature range can be exemplified by the range of 5° C. to60° C., and the temperature can also be adjusted as appropriate in therange from 10° C. to 55° C.

An additive, e.g., an essential oil, aroma extract, and so forth, may beadded in a freely selected amount in the manufacturing method accordingto the present invention in any step except between the smoke treatmentstep and the storage step.

A step of adjusting the moisture content of the obtained tobaccomaterial may be present after the storage step. By going through such astep, the moisture content of the tobacco material can be adjusted to 10to 20 wt % and preferably 10 to 15 wt % with reference to the totalamount of the tobacco material.

As indicated in the preceding, the manufacturing method according toembodiments of the present invention is performed prior to the executionof the treatments at the tobacco material processing site as shown inFIG. 1. The tobacco material yielded by the manufacturing methodaccording to the present invention is ordinarily stored in a warehouseand then transported to the tobacco material processing site (refer toFIG. 1). This storage in a warehouse is ordinarily for approximately 10to 180 days.

A tobacco material having the same component content as the <TobaccoMaterial> described in the following can be obtained in accordance withthe method for manufacturing a tobacco material that has been describedin the preceding.

<Tobacco Material>

The tobacco material according to embodiments of the present invention,for example, can be manufactured by the method according to the presentinvention as described above for manufacturing a tobacco material.

Leaf tobacco constituting the tobacco material according to embodimentsof the present invention is leaf tobacco prior to the execution ofstripping at the material processing site shown in FIG. 1, and isconstituted of leaf tobacco that has not been subjected to a lamina/stemseparation process (is unthreshed).

The types of leaf tobacco constituting the tobacco material according toembodiments of the present invention may be the same types as used inthe manufacturing method described above.

The tobacco material according to embodiments of the present inventionhas a constitution according to the following (1) to (4):

(1) the benzo[a]pyrene content is not more than 100 ng/g based on thedry weight of the tobacco material;

(2) the acetic acid content is not more than 20 mg/g based on the dryweight of the tobacco material;

(3) the guaiacol content is 5 to 5,000 μg/g based on the dry weight ofthe tobacco material; and

(4) the 2,6-dimethoxyphenol content is 10 to 10,000 μg/g based on thedry weight of the tobacco material.

In addition, the benzo[a]pyrene content of the tobacco materialaccording to embodiments of the present invention is more preferably notmore than 50 ng/g on a dry weight basis and is particularly preferablynot greater than the detection limit. A low amount of adhesion byharmful substances contained in the smoke is provided by having thebenzo[a]pyrene content be in this range.

When a tobacco material is produced by the manufacturing methoddescribed in the preceding, the benzo[a]pyrene content in the tobaccomaterial according to embodiments of the present invention can beadjusted by adjusting the material temperature of the smoke-producingmaterial when the smoke treatment is performed. For example, when a woodis used for the smoke-producing material provided to the aforementionedsmoke treatment, the content of specific polycyclic aromatic hydrocarboncan be limited into the range indicated above when the materialtemperature of the wood is adjusted into the range from 400° C. to 500°C.

In addition, the tobacco material according to embodiments of thepresent invention preferably has an acetic acid content of not more than20 mg/g on a dry weight basis and particularly preferably not more than15 mg/g on a dry weight basis.

A tobacco material exhibiting little irritation for the user is providedby having the acetic acid content be in the indicated range. The tobaccomaterial according to the present invention, on the other hand, maycontain acetic acid at or above 10 μg/g.

The propionic acid content in the tobacco material according toembodiments of the present invention is preferably not more than 1 mg/gon a dry weight basis and is particularly preferably not more than 0.5mg/g on a dry weight basis. In another embodiment, the tobacco materialaccording to the present invention can contain propionic acid at orabove 10 μg/g.

When the tobacco material is produced by the manufacturing methoddescribed above, the acetic acid content and propionic acid content inthe tobacco material according to embodiments of the present inventioncan be adjusted by adjusting the storage temperature and storage time.For example, when the storage time is extended, the amount ofvolatilized low molecular weight carboxylic acid is increased, and as aconsequence the content of low molecular weight carboxylic acids in thetobacco material can be further reduced.

The tobacco material according to embodiments of the present inventioncan be manufactured by the above-described manufacturing methodaccording to embodiments of the present invention; however, themanufacturing method according to embodiments of the present inventiondoes not contain the step of adding an alcohol in order to produce estercompounds that is described in WO 2014/203341. As a consequence, thetobacco material according to embodiments of the present inventionsubstantially does not contain the ester compounds described in WO2014/203341, for example, ethyl acetate and ethyl valerate. Here,“substantially does not contain” indicates at or below the detectionlimit.

The guaiacol content in the tobacco material according to the presentinvention is more preferably 5 to 5,000 μg/g on a dry weight basis andis particularly preferably 100 to 1,500 μg/g on a dry weight basis.

The 2,6-dimethoxyphenol content in the tobacco material according to thepresent invention is more preferably 10 to 10,000 μg/g on a dry weightbasis and is particularly preferably 500 to 2,000 μg/g on a dry weightbasis.

Guaiacol and 2,6-dimethoxyphenol are components specific to the smokeand are components that provide the user with smokiness, an aroma andtaste characteristic of tobacco materials, and a flavor with an impacton the perception of migrating from the oral cavity to the nasal cavity.

When the tobacco material is produced by the above-describedmanufacturing method, the content of the guaiacol and2,6-dimethoxyphenol in the tobacco material according to embodiments ofthe present invention can be adjusted by adjusting the duration of thesmoke treatment. For example, the duration of the smoke treatment isextended when a greater addition of these components is sought.

The ratio between the 2,6-dimethoxyphenol content and the guaiacolcontent (also referred to as the 2,6-DMP/G ratio in the following) inthe tobacco material according to embodiments of the present inventionis preferably 1 to 20, more preferably 2 to 15, and particularlypreferably 2 to 10.

Having the 2,6-DMP/G ratio be in the indicated range makes it possibleto provide the user with a good balance of smokiness, an aroma and tastecharacteristic of tobacco materials, and an impact on the perception ofmigrating from the oral cavity to the nasal cavity.

This 2,6-DMP/G ratio can be adjusted by changing, for example, thesmoking conditions (type of wood chip, pyrolysis temperature, and soforth) and the storage conditions (temperature, extent of contact withair, duration, and so forth).

For example, the 2,6-DMP/G ratio declines when the material temperatureof the smoke-producing material in the smoke treatment step is raised;the 2,6-DMP/G ratio increases when the temperature that is a conditionof storage is raised. In addition, the 2,6-DMP/G ratio increases whenthe extent of contact with air that is a storage condition is increased.The 2,6-DMP/G ratio also increases when the duration of storage isextended.

In conventional DFC, because a drying treatment is not carried out priorto the smoke treatment, the moisture content of the leaf tobacco issubstantially higher than for the leaf tobacco according to the presentinvention and the amount of adhesion by 2,6-dimethoxyphenol to the leaftobacco is smaller. In addition, in conventional DFC, the materialtemperature of the smoke-producing material in the smoke treatment ishigher than in the present invention and as a consequence 2,6-DMP/Gassumes a declining trend. Accordingly, the 2,6-DMP/G ratio inconventional DFC is presumed to be smaller than the 1 that is the lowerlimit on the range indicated above.

The ratio between the 2,6-dimethoxyphenol content and the phenol content(also referred to as the 2,6-DMP/P ratio) in the tobacco materialaccording to embodiments of the present invention is preferably 1 to100, more preferably 5 to 70, and particularly preferably 20 to 50.

The smoky sensation is made more prominent by having the 2,6-DMP/P ratiobe in the indicated range.

This 2,6-DMP/P ratio, for example, is reduced when the materialtemperature of the smoke-producing material in the smoke treatment stepis increased, and is reduced when the duration of storage that is acondition of storage is extended. It is also reduced when thetemperature during storage is increased.

In conventional DFC, because a drying treatment is not carried out priorto the smoke treatment, the moisture content of the leaf tobacco issubstantially higher than in the leaf tobacco according to the presentinvention and the amount of adhesion by 2,6-dimethoxyphenol to the leaftobacco is smaller. Accordingly, the 2,6-DMP/P ratio in conventional DFCis presumed to be smaller than the 1 that is the lower limit on therange indicated above.

The ratio between the guaiacol content and the phenol content (alsoreferred to as the G/P ratio) in the tobacco material according toembodiments of the present invention is preferably 0.5 to 12.0, morepreferably 0.5 to 6.0, and particularly preferably 2.0 to 5.0.

The smoky sensation is made prominent by having the G/P ratio be in theindicated range.

This G/P ratio, for example, is reduced when the material temperature ofthe smoke-producing material in the smoke treatment step is increased,and the G/P ratio is reduced when the temperature that is a condition ofstorage is increased.

The moisture content for the tobacco material according to embodimentsof the present invention can be, for example, 10 to 20 wt % in anembodiment and is preferably 10 to 15 wt %.

The content of polycyclic aromatic hydrocarbon (benzo[a]pyrene) in thetobacco material can be determined by the following method.

0.5 g of dried shredded tobacco is accurately weighed into a glassscrew-cap vial (capacity=20 mL); 200 μL of internal reference substance(deuterated form of the particular polycyclic aromatic hydrocarbon) and10 mL of cyclohexane as extraction solvent are added; the cap isapplied; and extraction is carried out by shaking at 190 rpm for 30minutes at room temperature. The supernatant is filtered across a0.45-μm membrane filter and is subsequently concentrated to 1 mL,purified and concentrated on a solid-phase extraction SPE column (SPE:Si 2 g/12 cc, small amount of Na₂SO₄), and then dispensed into a GCvial. Analysis is carried out with a GCMS equipped with an autosampler,and the amount of each target component in the sample is quantitated bythe internal reference method.

The following conditions can be used for the GC/MS conditions.

<GC/MS Analysis Conditions>

Instrument: gas chromatography analysis instrument (5975N) from AgilentTechnologies, Inc.

Injection Port Conditions:

Injection port temperature: 300° C.;

Injection method: pulsed spitless; and

Injection amount: 1 μL

Analysis column: DB-17 ms from Agilent Technologies, Inc., 30 m×0.25mm×0.25 μmColumn flow rate: 1.2 mL/min. (He)

Temperature Ramp Conditions:

Initial: 60° C. (1 min); then 15° C./min to 150° C. (0.5 min); then 5°C./min to 320° C. (18.5 min); then Run time (60 min.) MS conditions:

Ion source: 300° C.;

Quadrupole: 180° C.;

SIM mode

The contents of the low molecular weight carboxylic acids in the tobaccomaterial, starting with acetic acid, and the contents of the flavorcomponents (guaiacol, 2,6-dimethoxyphenol, phenol) in the tobaccomaterial can be determined by the following method.

0.5 g of the dried and ground tobacco material is accurately weighedinto a glass screw-cap vial (capacity=20 mL) and 0.05 μg quinoline isadded as an internal reference substance. 10 mL of methanol is added asextraction solvent; the cap is applied; and extraction is carried out byshaking at 200 rpm for 60 minutes at room temperature. The supernatantis filtered across a 0.45-μm membrane filter and is then transferredinto a GC vial; analysis is carried out with a GC/MS equipped with anautosampler. The amount of the analysis target component contained ineach sample is quantitated by determining the ratio between the peakareas for the analysis target component and quinoline on the obtained GCchromatogram.

The following conditions can be used for the GC/MS conditions.

Instrument: gas chromatography analysis instrument (6890N) from AgilentTechnologies, Inc., and mass detector (5973N) from Agilent Technologies,Inc.Amount injected: 1 μL (injection in pulsed splitless mode) Column:HP-INNOWAX (30 m×0.25 mm (0.25 μm film thickness)) from AgilentTechnologies, Inc.Oven: 40° C.→260° C. (5° C./rain)Mass detector: TIC mode (mass numbers 29 to 550)

<Tobacco Product>

The tobacco material according to embodiments of the present inventionis a unstripped tobacco material in which the lamina and stems remainpresent as such.

Accordingly, when the tobacco material according to embodiments of thepresent invention is used to produce a tobacco product as exemplifiedhereinafter, it can be used as a starting material for the tobaccoproduct by going through a stripping step and separation step at thematerial processing site as shown in FIG. 1. Thus, in anotherembodiment, the hereabove-described method for manufacturing a tobaccomaterial includes stripping and separation steps after the step ofstoring the smoke-treated unstripped leaf tobacco under semi-sealedconditions.

The starting material shipped from the material processing site shown inFIG. 1 may be blended at a manufacturing plant in any proportions with,for example, an ordinary tobacco material, and a cigarette may beproduced using this blended starting material.

In addition, the tobacco material according to embodiments of thepresent invention may be disposed in a filter portion of a knowncigarette, for example, in a form of a blend in any proportions with anordinary shredded tobacco. The disposition in the filter portion may be,for example, a disposition within a cavity or may be a dispositiondispersed in the filter fiber.

The tobacco material may also be used in a heating flavor inhaler or inan unheated flavor inhaler.

When the tobacco material according to embodiments of the presentinvention is used in a cigarette or heating flavor inhaler, the user maythen enjoy the flavor generated by the specific flavor componentsdescribed above.

A “heating flavor inhaler” is an inhaler in which the tobacco materialis heated without combustion and the user experiences the flavor of theheated tobacco material by inhalation. Examples are a carbon heatsource-type inhaler in which a tobacco material is heated by thecombustion heat of a carbon heat source (refer, for example, to WO2006/073065), an electrically heated inhaler provided with an inhalerand a heating device for electrically heating the inhaler (refer, forexample, to WO 2010/110226), and a liquid atomization inhaler in which aliquid aerosol source containing a tobacco material is atomized byheating (refer, for example, to WO 2015/046385).

Among these, the electrically heated flavor inhaler contains, interalia, a mouthpiece, a main unit containing an electronic heater and acontainer holding a composition that contains a tobacco material, and atemperature controller for controlling the temperature of the electronicheater. The specific structure described in Japanese Translation of PCTApplication No. 2014-524313 can be used. The container holding thetobacco material-containing composition can be, for example, a pod.

The tobacco material according to embodiments of the present inventionmay be contained the above-mentioned container, for example, in a formof a blend in any proportions with the ordinary shredded tobacco. Thematerial of a container to contain the tobacco material according toembodiments of the present invention is not particularly limited, andexamples thereof include a metal with high thermal conductivity such asaluminum.

When used in the aforementioned heating flavor inhaler, the tobaccomaterial according to embodiments of the present invention may be storedin the container in the form of a composition containing, for example, ablend of the tobacco material according to embodiments of the presentinvention in any proportions with, for example, an ordinary shreddedtobacco, and also containing a polyhydric alcohol such as glyceroland/or propylene glycol, a thickener, and other optional components suchas a fragrance.

In a preferred embodiment, the composition used in a heating flavorinhaler contains the tobacco material according to embodiments of thepresent invention, a polyhydric alcohol, and a thickener.

The size of each leaf tobacco present in the tobacco material is alsonot particularly limited, and the sizes used in common electricallyheated flavor inhalers can be used.

The weight proportion of the tobacco material according to embodimentsof the present invention in the composition filled in the container canbe, for example, approximately 10% to 40%.

In the case of liquid atomization inhalers in which a liquid aerosolsource containing a tobacco material is atomized by heating, the tobaccomaterial according to embodiments of the present invention may be usedas a portion of the starting material for producing the liquid flavorsource inserted in the liquid reservoir.

Snus is an example of the use of the tobacco material according toembodiments of the present invention as an oral tobacco product. In thiscase, production is carried out by filling, using a known method, ablend in any proportions of a tobacco material produced by theabove-described manufacturing method with, for example, a commonshredded tobacco, into a packaging material that uses a startingmaterial such as, for example, a nonwoven fabric. For example, thetobacco material in an adjusted amount may be filled and sealed by anymeans such as heat sealing to obtain snus.

There are no particular limitations on the packing material that may beused, but, for example, a cellulosic nonwoven fabric is preferably used.

When the oral tobacco product is, for example, a gum, production iscarried by blending, using a known method, a known gum base with theabove-described tobacco material obtained using the manufacturing methodaccording to embodiments of the present invention. Also with regard tochewing tobacco, pipe tobacco, and compressed tobacco, production can becarried out using known methods, but using the above-described tobaccomaterial obtained using the manufacturing method according toembodiments of the present invention. Also with regard to edible films,production can be carried out using known materials and methods, butusing the above-described tobacco material obtained using themanufacturing method according to embodiments of the present invention.

The manufacturing method according to embodiments of the presentinvention solves, for example, the problem of the adhesion to leaftobacco of polycyclic aromatic hydrocarbon present in smoke produced ata temperature at which the occurrence of incomplete combustion isfacilitated, a point that has been a problem for tobacco materialsubjected to a conventional smoke treatment such as DFC, and solves theproblem of the production of irritating substances such as acetic acid,while providing a tobacco material in which components exhibiting thecharacteristic flavor of smoke are increased.

The tobacco material manufactured with the method according to thepresent invention may be used as a portion of the tobacco material intobacco products. The tobacco material yielded by the present invention,when used as a portion of the tobacco material in a tobacco product, maybe used in any proportion.

EXAMPLES

The present invention is more specifically described using examples, butthe present invention is not limited to the description in the followingexamples as long as the essential features of the present invention arenot exceeded.

Experimental Example 1 Leaf Tobacco Drying Treatment

Immediately after harvesting, leaf tobacco was air-dried in a dryingroom impermeable to direct sunlight, by row drying or stem drying, forapproximately 1 month in the temperature range from 25° C. to 35° C.

The post-drying moisture content of the leaf tobacco was adjusted to be5 to 50 wt % for each sample.

Smoke Treatment of Leaf Tobacco

A Compact Smoker (Snow Peak Inc.) was used for the smoking apparatus.Approximately 20 g of wood chips was placed in the bottom; approximately10 g of the unstripped leaf tobacco, dried as described above, wasstacked on the upper level; and the lid was applied. This was placed,with the bottom of the smoking apparatus grounded, on atemperature-controllable heating apparatus (AS ONE Corporation, HotPlate CHR-250DN). The set temperature of the heating apparatus was setto 500° C. and the wood chips were pyrolyzed. Ten minutes was used forthe pyrolysis time of the wood chips, and white oak, hickory, oak, orwalnut was used as the smoke-producing material.

The material temperature of the smoke-producing material was adjusted tobe approximately from 300° C. to 600° C.

Storage Treatment of Leaf Tobacco

The smoke-treated material was introduced into a zip-equipped vinyl bag(Seisannipponsha Ltd.) and Lamizip AL-E (Seisannipponsha Ltd.). Asemi-sealed system was set up by closing the top of the zip-equippedvinyl bag into a lightly collapsed configuration. The top of the LamizipAL-E, on the other hand, was heat sealed to set up a completely sealedsystem. These bags were stored in a thermostatted room at a temperatureof 22° C. and a humidity of 62%. The duration of storage was up to 4months.

<Differences in Content of Benzo[a]Pyrene, Guaiacol, and2,6-Dimethoxyphenol Based on Differences in Temperature of SmokeTreatment of Leaf Tobacco>

The benzo[a]pyrene content, guaiacol content, and 2,6-dimethoxyphenolcontent were each measured on the leaf tobacco provided by carrying outthe smoke treatment at a material temperature for the smoke-producingmaterial of 300° C., 400° C., 450° C., 500° C., or 600° C. on the leaftobacco provided by the drying treatment described in ExperimentalExample 1 (moisture content: 13 wt %). For reference, the contents weremeasured for the original raw material, i.e., the untreated leaftobacco, and the contents were also measured for conventional DFC(execution of a smoke treatment on the tobacco leaf hung as such in astate without separation of the stems from the lamina).

(1) Benzo[a]Pyrene

The results of the benzo[a]pyrene measurements are given in FIG. 2.

As is clear from FIG. 2, the content of benzo[a]pyrene was low at 300°C. to 500° C., while the benzo[a]pyrene content was dramaticallyincreased at 600° C. This shows that benzo[a]pyrene is present at highcontents in leaf tobacco yielded by the execution of a smoke treatmentat a temperature in excess of 600° C., as in conventional DFC.

For comparison, the benzo[a]pyrene content in the original raw materialis also given in FIG. 2.

The benzo[a]pyrene contents given in FIG. 2 are collected in thefollowing Table 1.

TABLE 1 material temperature of smoke-producing material (° C.) BaP(ng/g-DB) 300 4.4 400 5.1 450 5.4 500 4.8 600 26.2 * BaP content oforiginal raw material: 3.6 ng/g-DB, BaP content for conventional DFC:600.5 ng/g-DB

(2) Guaiacol

The results of the guaiacol measurements are given in FIG. 3.

As is clear from FIG. 3, it was demonstrated that guaiacol was containedin the leaf tobacco in large amounts when the material temperature ofthe smoke-producing material was 400° C. to 500° C., and that guaiacolwas contained in the largest amount at 450° C. The content of guaiacolcontained in the original raw material and the guaiacol content forconventional DFC are also shown in FIG. 3 for comparison. As shown inFIG. 3, almost no guaiacol is present in the original raw material. Thisis because guaiacol is produced by the pyrolysis of lignin and isprovided to the leaf tobacco by smoke treatment.

(3) 2,6-Dimethoxyphenol

The measurement results for 2,6-dimethoxyphenol are shown in FIG. 4.

As is clear from FIG. 4, it was demonstrated that 2,6-dimethoxyphenolwas contained in the leaf tobacco in large amounts when the materialtemperature of the smoke-producing material was 400° C. to 500° C. Thecontent of 2,6-dimethoxyphenol contained in the original raw materialand the 2,6-dimethoxyphenol content for conventional DFC are also shownin FIG. 4 for comparison.

As shown in FIG. 4, almost no 2,6-dimethoxyphenol is present in theoriginal raw material. This is because 2,6-dimethoxyphenol is producedby the pyrolysis of lignin and is provided to the leaf tobacco by smoketreatment.

The guaiacol content and 2,6-dimethoxyphenol content are collected inthe following Table 2.

TABLE 2 material temperature of smoke-producing 2,6-dimethoxyphenolmaterial (° C.) guaiacol (μg/g-DB) (μg/g-DB) 300 32.0 828.3 400 137.62672.4 450 228.1 2654.1 500 152.0 2406.4 600 88.0 1334.3 * Original rawmaterial: guaiacol content = 1.3 μg/g-DB, 2,6-dimethoxyphenol content =8.4 μg/g-DB * Conventional DFC: guaiacol content = 52.7 μg/g-DB,2,6-dimethoxyphenol content = 1043.1 μg/g-DB

<Relationship Between Moisture Content of Leaf Tobacco Prior to SmokeTreatment and Guaiacol Adhesion Efficiency and 2,6-DimethoxyphenolAdhesion Efficiency>

In order to elucidate the relationship between the moisture content ofthe leaf tobacco after the drying treatment (before the smoke treatment)in Experimental Example 1 and the adhesion efficiency to the leaftobacco of guaiacol and 2,6-dimethoxyphenol due to the smoke treatment,tests were carried out using the apparatus shown in FIG. 5 instead ofthe smoke treatment described for Experimental Example 1.

In the apparatus in FIG. 5, leaf tobacco 3 that has undergone the dryingtreatment in Experimental Example 1 is placed in the center of theinterior of the cylinder and a filter 4 is placed on the downstream sideof the air flow therefrom. A smoke treatment was performed by heatingthe smoke-producing material 1 using a hot plate 2, and the followingwere measured: the amount of guaiacol and the amount of2,6-dimethoxyphenol adhered to the leaf tobacco 3 and the amount ofguaiacol and the amount of 2,6-dimethoxyphenol adhered to the filter 4.

The adhesion efficiencies were calculated using the following formula.

adhesion efficiency (%)=amount of guaiacol or 2,6-dimethoxyphenoladhered to the leaf tobacco/(amount of guaiacol or 2,6-dimethoxyphenoladhered to the leaf tobacco+amount of guaiacol or 2,6-dimethoxyphenoladhered to the filter)×100

For guaiacol and 2,6-dimethoxyphenol, plots are given in FIGS. 6 and 7,respectively, in which the moisture content after the drying treatment(before the smoke treatment) is plotted on the horizontal axis and theadhesion efficiency is plotted on the vertical axis.

Results for Adhesion Efficiency

The adhesion efficiency for both guaiacol and 2,6-dimethoxyphenol wasincreased when the moisture content of the leaf tobacco after the dryingtreatment (before the smoke treatment) was 15 to 25 wt %. A moisturecontent for the leaf tobacco after the drying treatment in excess of 30wt % is unfavorable because fermentation due to the action ofmicroorganisms present in the leaf tobacco may then advance and thebalance among the components of the leaf tobacco may be disrupted.

<Timewise Variation in Contents of Acetic Acid and Propionic Acid inLeaf Tobacco During Storage Under Semi-Sealed and Sealed Conditions>

The post-smoke-treatment leaf tobacco provided by Experimental Example 1was stored in a semi-sealed system and in a sealed system, and theacetic acid and propionic acid contents were measured when 0, 1, 2, 3,and 4 months had elapsed for the duration of storage. The temperatureduring storage was 22° C. at 66% RH. The moisture content of the leaftobacco upon storage was 15 wt %.

The results for propionic acid are given in FIG. 8, and the results foracetic acid are given in FIG. 9.

According to the results in FIGS. 8 and 9, the propionic acid and aceticacid contents for storage in a semi-sealed system were reduced fromthose for storage in a sealed system with greater elapsed time andparticularly when the duration of storage reached 4 months.

<Timewise Variation in Contents of Propionic Acid and Acetic Acid inLeaf Tobacco During Storage Under Semi-Sealed Conditions (AcceleratedTesting)>

The post-smoke-treatment leaf tobacco provided by Experimental Example 1was submitted to storage in a semi-sealed system using acceleratedtesting (40° C., 60% RH). Four months in this accelerated testing ishypothesized to correspond to approximately 24 months of testing at 22°C. The results for propionic acid are given in FIG. 10, and the resultsfor acetic acid are given in FIG. 11.

The results in FIGS. 10 and 11 demonstrated that the propionic acidcontent and acetic acid content in the stored leaf tobacco underwent anongoing decline as the duration of storage in the semi-sealed systemgrew longer.

INDUSTRIAL APPLICABILITY

The manufacturing method according to the present invention can providea tobacco material that has a low benzo[a]pyrene content and a lowcontent of low molecular weight carboxylic acids such as acetic acid andpropionic acid and that contains large amounts of specific flavorcomponents.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. A method for manufacturing a tobacco material,comprising the steps of: drying a post-harvest unstripped leaf tobaccoto a moisture content of 10 to 25 wt %; subjecting the dried unstrippedleaf tobacco to a smoke treatment with a smoke provided by pyrolysis ofa smoke-producing material in a material temperature range of 400° C. to500° C.; and, subsequent to the smoke treatment step, storing thesmoke-treated unstripped leaf tobacco under a semi-sealed condition. 2.The method for manufacturing a tobacco material according to claim 1,wherein the drying of the post-harvest unstripped leaf tobacco iscarried out to a moisture content thereof of 15 to 20 wt %.
 3. Themethod for manufacturing a tobacco material according to claim 1,wherein the storing step is carried out at room temperature for aduration of at least 3 months but less than 24 months.
 4. The method formanufacturing a tobacco material according to claim 1, wherein thetobacco material yielded by the manufacturing method has a constitutionaccording to the following (1) to (4): (1) a benzo[a]pyrene content isnot more than 100 ng/g based on the dry weight of the tobacco material;(2) an acetic acid content is not more than 20 mg/g based on the dryweight of the tobacco material; (3) a guaiacol content is 5 to 5,000μg/g based on the dry weight of the tobacco material; and (4) a2,6-dimethoxyphenol content is 10 to 10,000 μg/g based on the dry weightof the tobacco material.
 5. A tobacco material constituted of a leaftobacco that has not been subjected to a lamina/stem separation process,wherein the tobacco material has a constitution according to thefollowing (1) to (4): (1) a benzo[a]pyrene content is not more than 100ng/g based on the dry weight of the tobacco material; (2) an acetic acidcontent is not more than 20 mg/g based on the dry weight of the tobaccomaterial; (3) a guaiacol content is 5 to 5,000 μg/g based on the dryweight of the tobacco material; and (4) a 2,6-dimethoxyphenol content is10 to 10,000 μg/g based on the dry weight of the tobacco material.
 6. Atobacco product comprising the tobacco material according to claim
 5. 7.The tobacco product according to claim 6, which is a cigarette or aheating flavor inhaler.